The Earliest Genetic Snapshot: Non- Invasive Prenatal Testing Is Coming of Age

Today, more than one in five pregnant women in the US gets her blood drawn when she’s about ten weeks pregnant, not to gauge her own health, but to capture an early snapshot of her baby’s genome. Her blood sample is sent to one of a handful of companies that carry out noninvasive prenatal testing (NIPT); Sequenom’s MaterniT21 was the first and is the most widely used. The tests rely on fragments of fetal DNA that are free-floating in the mom-to-be’s bloodstream; by tallying DNA fragments from each chromosome, scientists can pinpoint whether the fetus has an extra, or missing, chromosome—suggesting a risk for Downs Syndrome or other chromosomal aneupoloidies— and whether they have the telltale Y chromosome of a male or the double dose of X that
signifies a girl.